Why generated ViewDataBinding class annotates property for "include" tag as Nullable

Question

I'm using Android Data Binding library to bind an xml layout that has an <include>

layout.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>
        <variable
            name="model"
            type="com.example.MyViewModel" />
    </data>

    ...

    <include
        layout="@layout/someOtherLayout"
        android:id="@+id/includedLayout" />
    ...

</layout>

In the generated Databinding class for the xml I see this property:

@Nullable
public final com.example.databinding.SomeOtherLayoutBinding includedLayout;

Why is it annotated as @Nullable? The <include> is in the layout and as I see it, it is obviously non-null. What am I missing?

It forces me to use non-null assertion operator !! in Kotlin code when accessing the fields of the included layout and I'm wondering if it is safe or if there is something I'm not considering here

val binder = DataBindingUtil.bind(view)
val someView = binder.includedLayout!!.someView

Answer 1

According to the Documentation on View Binding, when you have multiple layouts for configuration changes, if the view is only present in some configurations, the binding class will be marked as nullable.

View Binding Docs